In the manufacture of appliances such as hot beverage makers and, more particularly, coffee brewers, it has become desirable to employ microwave energy as the source for heating the fluid used for making the beverage. Such devices require the use of a valve to control the flow of the fluid from one portion of the device to a second portion. Such a valve may be made of a plastic housing containing an actuator of metal, such as a bimeltal element, which operates at selected temperature levels. Other valves may be made entirely of plastic or entirely of metal and may be thermally or manually actuated.
One particularly desirable thermally actuated valve for normally heated beverage-making appliances is shown and described in U.S. Pat. Nos. 3,972,273, and 4,025,042. These are valves which utilize a plastic housing containing metal component parts.
It is sometimes desirable, however, to employ all-metal valves. This has in the past proved impractical in microwave devices, however, since metal has produced arcing and other undesirable effects when subjected to microwave radiation, which effects cause considerable damage to the beverage-maker appliance.